Search engines enable users to search for web pages and other content on the Internet. Generally, users can submit queries to a search engine system. For example, a user may submit a query using a web browser at a client computing device. The browser may send the query as a hypertext transfer protocol (HTTP) request. The HTTP request containing the query may be sent to a server. The server, in turn, sends the request onto a search engine system. The search engine system uses the query to identify web pages and other content that satisfy the query. The search engine system then returns a set of search results to the server. The server generates a page to display the set of search results to the user. For example, the page may be encoded in hypertext markup language (HTML). The server then sends the page to the client as an HTTP response. Finally, the web browser renders the page at the client computing device for display to the user.